Field of the Invention
This invention relates to electric plugs and, more particularly, to a novel and highly-effective universal electric plug that will mate properly with electric receptacles that respectively have substantially different configurations.
A conventional electric plug that will mate properly with an electric receptacle of a first configuration will not in general mate properly with an electric receptacle of a second configuration that is substantially different from the first.
The problem of providing an electric plug that is properly configured to mate with the receptacle with which it is to be connected electrically arises in many environments. For example, international travelers who carry small plug-in electric appliances such as hair dryers and electric shavers must also carry adapters in order to employ the appliances in different countries that have household electric receptacles conforming to respectively different design specifications.
Even within the confines of a single country, the design specifications for electric receptacles in certain environments may not be standardized. For example, in the case of cordless telephones sold in the United States, wherein the handset is powered by a rechargeable battery pack, there are at least three different designs of plug receptacles.
There are an estimated 30 million cordless telephones in the United States, and the number is expected to increase annually in the foreseeable future. To allow for the replacement of the nickel-cadmium batteries in the telephone handset and to facilitate the separate disposal of the phone and the battery, most of the battery packs are provided with simple modular plugs for insertion into matching receptacles in the telephone handsets. There are, however, three major manufacturers of these plugs and sockets, namely JST, Molex and Mitsumi, and the plugs and mating receptacles made by these manufacturers are all shaped differently from one another. In order to accommodate the different requirements of different phones, there are already nearly two dozen configurations for assembling different unit cells into three- or four-cell battery packs. This, when combined with three different types of plugs and mating receptacles, makes for a bewildering series of replacement battery packs from which the consumer must select in order to replace a battery pack. It also creates serious inventory problems for manufacturers, distributors and retailers of replacement battery packs.
Because of the seriousness of the problem, many attempts have been made heretofore to develop universal plugs and other devices for simplifying the task of users in making electrical connections of various kinds with various pieces of equipment. Mention has already been made above of the adapters sold to international travelers by means of which they can use a small plug-in electric appliance such as a hair dryer or electric shaver designed, for example, for the U.S. market in various other countries where the electric receptacles for supplying household current are designed to different specifications.
A U.S. Pat. No. 4,191,917 to Brown et al. discloses a relatively flat, rectangular, box-shaped, rechargeable battery pack that has a multi-positionable plug with prongs. The plug can be appropriately positioned for recharging the pack by insertion Of the plug into either a European-type, deeply recessed receptacle, in a shallow recessed receptacle or in a flush, non-recessed United States-type receptacle. The pack is adapted to interchangeably fit into a pocket or any one of a plurality of pockets in a device in which the pack is to be employed. The prongs on the plug furnish voltage to the device when the pack is in a device pocket and furnish voltage to the pack during recharging. In a discharge mode, the plug is depressed and latched within the battery pack leaving only the prongs external of the battery pack for insertion into the device to be powered. The plug is likewise depressed for recharging in a flush-type receptacle. The pack discharge circuitry is actuated by a mating post in the housing of the device to be powered.
A U.S. Pat. No. 4,597,627 to Wondra et al. discloses a multiple signal cable system having a plurality of individual plug heads formed at the free ends of the cables for connection to a corresponding number of counter-piece contacts on a unitary adapter. The apparatus disclosed in the patent permits a multiple signal cable system having a plurality of individual plug heads formed at the free ends of the cables for connection to a corresponding number of counter-piece contacts on a unitary adapter. The invention disclosed in the patent permits a simplified manipulation of the multiple plug heads for connection with the adapter, while also affording rearrangement of the sequence of individual plug heads in accordance with the particular adapter. The individual plug heads are connected together in a consolidated, unitary arrangement by means of a housing collar having a sequence of side-by-side chambers for respectively securing the plug heads tightly therein. Lock means are provided on the housing and plug heads to secure the plug heads against relative movement and prevent the individual plug heads from falling out or being withdrawn from the unitary arrangement; however, the lock means are releasable to permit removal or rearrangement of the plug heads as needed.
None of the prior art described above provides a totally satisfactory solution to the problem of mating a plug properly with electric receptacles that respectively have substantially different configurations.